Because of the low contrasts occurring in specific body regions, it is advantageous for the purpose of displaying such regions using tomographic methods, in particular in the field of computer aided tomography or NMR tomography, to apply contrast media in the display process, and thus to obtain a more contrasted image of these body regions. However, contrast media mostly have the disadvantage that they are biologically incompatible, and their dose is therefore to be held as low as possible. Because of the biological variability of the bodies being examined, however, it is not possible to make a sufficiently accurate and generally valid statement on how the concentration profile of a specific contrast medium administration will develop over time at an observed site in the body. Thus, it is necessary in the case of each body examined to use a test injection of a contrast medium or a test bolus administration as a basis for observing the effect thereof, in particular the time profile, following thereupon, of the concentration values at the site of interest in the body to be examined.
In the case of application in conjunction with a CT examination, over a specific time period after the test bolus injection, and with the use of the lowest possible radiation doses, the concentration is measured in this case indirectly via the changes produced there in the HU values. Since only the imaging effect of the contrast medium is of interest, and there is a linear relationship between the imaging action and concentration of the contrast medium, a statement on the absolute concentration of the contrast medium remains open and trivial. Again, the resolution of the images of such a test examination remains low.
It is known for knowledge of the effect of such a test bolus administration and the assumption of a linear cause/effect relationship to be used as a basis for precalculating the effect of a correct or envisaged contrast medium administration, and thus for determining the dose of contrast medium that is required to attain a sufficient image contrast during a tomographic examination. However, in the case of the known method the calculability is limited to a time period that is equivalent to the preceding measurement of a test bolus administration. It is certainly possible to interpolate values in this time span, but extrapolating beyond the test time period, specifically in both time directions, is possible only in a very limited fashion. Where there has been a need for any type of reasons for the test measurement to be limited in time, the prediction time period largely to be assumed as reliable has so far also been correspondingly limited.
Specific reference is made to the patent applications (not prior publications) with file references DE 10 2005 006 659.3 and 10 2005 006 657.7. The disclosure content of each of these references is incorporated in this application by reference in their entirety, and specifically with regard to the precalculation of a required contrast medium flow on the basis of a known cause/effect relationship of a previously administered test bolus for the purpose of achieving a desired contrast in an observed region of an examined patient, in particular the calculation formulas represented there.
The previously cited applications also only disclose how it is possible to calculate a required contrast medium administration. The interaction of the calculation method with the planning of a tomographic examination is not specified. All that is known so far is a manual calculation and subsequent manual transfer of the calculated parameters to the automatic control of a contrast medium injector. Such a transfer is time consuming and contains many sources of error.